ipc/mqueue.c

   1 /*
   2  * POSIX message queues filesystem for Linux.
   3  *
   4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
   5  *                          Michal Wronski          (michal.wronski@gmail.com)
   6  *
   7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
   8  * Lockless receive & send, fd based notify:
   9  *                          Manfred Spraul          (manfred@colorfullife.com)
  10  *
  11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
  12  *
  13  * This file is released under the GPL.
  14  */
  15
  16 #include <linux/capability.h>
  17 #include <linux/init.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/file.h>
  20 #include <linux/mount.h>
  21 #include <linux/namei.h>
  22 #include <linux/sysctl.h>
  23 #include <linux/poll.h>
  24 #include <linux/mqueue.h>
  25 #include <linux/msg.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/netlink.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/audit.h>
  30 #include <linux/signal.h>
  31 #include <linux/mutex.h>
  32 #include <linux/nsproxy.h>
  33 #include <linux/pid.h>
  34
  35 #include <net/sock.h>
  36 #include "util.h"
  37
  38 #define MQUEUE_MAGIC    0x19800202
  39 #define DIRENT_SIZE     20
  40 #define FILENT_SIZE     80
  41
  42 #define SEND            0
  43 #define RECV            1
  44
  45 #define STATE_NONE      0
  46 #define STATE_PENDING   1
  47 #define STATE_READY     2
  48
  49 /* default values */
  50 #define DFLT_QUEUESMAX  256     /* max number of message queues */
  51 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
  52 #define HARD_MSGMAX     (131072/sizeof(void*))
  53 #define DFLT_MSGSIZEMAX 8192    /* max message size */
  54
  55 /*
  56  * Define the ranges various user-specified maximum values can
  57  * be set to.
  58  */
  59 #define MIN_MSGMAX      1               /* min value for msg_max */
  60 #define MAX_MSGMAX      HARD_MSGMAX     /* max value for msg_max */
  61 #define MIN_MSGSIZEMAX  128             /* min value for msgsize_max */
  62 #define MAX_MSGSIZEMAX  (8192*128)      /* max value for msgsize_max */
  63
  64 struct ext_wait_queue {         /* queue of sleeping tasks */
  65         struct task_struct *task;
  66         struct list_head list;
  67         struct msg_msg *msg;    /* ptr of loaded message */
  68         int state;              /* one of STATE_* values */
  69 };
  70
  71 struct mqueue_inode_info {
  72         spinlock_t lock;
  73         struct inode vfs_inode;
  74         wait_queue_head_t wait_q;
  75
  76         struct msg_msg **messages;
  77         struct mq_attr attr;
  78
  79         struct sigevent notify;
  80         struct pid* notify_owner;
  81         struct user_struct *user;       /* user who created, for accounting */
  82         struct sock *notify_sock;
  83         struct sk_buff *notify_cookie;
  84
  85         /* for tasks waiting for free space and messages, respectively */
  86         struct ext_wait_queue e_wait_q[2];
  87
  88         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  89 };
  90
  91 static const struct inode_operations mqueue_dir_inode_operations;
  92 static const struct file_operations mqueue_file_operations;
  93 static struct super_operations mqueue_super_ops;
  94 static void remove_notification(struct mqueue_inode_info *info);
  95
  96 static spinlock_t mq_lock;
  97 static struct kmem_cache *mqueue_inode_cachep;
  98 static struct vfsmount *mqueue_mnt;
  99
 100 static unsigned int queues_count;
 101 static unsigned int queues_max  = DFLT_QUEUESMAX;
 102 static unsigned int msg_max     = DFLT_MSGMAX;
 103 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
 104
 105 static struct ctl_table_header * mq_sysctl_table;
 106
 107 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 108 {
 109         return container_of(inode, struct mqueue_inode_info, vfs_inode);
 110 }
 111
 112 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 113                                                         struct mq_attr *attr)
 114 {
 115         struct user_struct *u = current_user();
 116         struct inode *inode;
 117
 118         inode = new_inode(sb);
 119         if (inode) {
 120                 inode->i_mode = mode;
 121                 inode->i_uid = current_fsuid();
 122                 inode->i_gid = current_fsgid();
 123                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 124                                 CURRENT_TIME;
 125
 126                 if (S_ISREG(mode)) {
 127                         struct mqueue_inode_info *info;
 128                         struct task_struct *p = current;
 129                         unsigned long mq_bytes, mq_msg_tblsz;
 130
 131                         inode->i_fop = &mqueue_file_operations;
 132                         inode->i_size = FILENT_SIZE;
 133                         /* mqueue specific info */
 134                         info = MQUEUE_I(inode);
 135                         spin_lock_init(&info->lock);
 136                         init_waitqueue_head(&info->wait_q);
 137                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 138                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 139                         info->messages = NULL;
 140                         info->notify_owner = NULL;
 141                         info->qsize = 0;
 142                         info->user = NULL;      /* set when all is ok */
 143                         memset(&info->attr, 0, sizeof(info->attr));
 144                         info->attr.mq_maxmsg = msg_max;
 145                         info->attr.mq_msgsize = msgsize_max;
 146                         if (attr) {
 147                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 148                                 info->attr.mq_msgsize = attr->mq_msgsize;
 149                         }
 150                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 151                         mq_bytes = (mq_msg_tblsz +
 152                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 153
 154                         spin_lock(&mq_lock);
 155                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 156                             u->mq_bytes + mq_bytes >
 157                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 158                                 spin_unlock(&mq_lock);
 159                                 goto out_inode;
 160                         }
 161                         u->mq_bytes += mq_bytes;
 162                         spin_unlock(&mq_lock);
 163
 164                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 165                         if (!info->messages) {
 166                                 spin_lock(&mq_lock);
 167                                 u->mq_bytes -= mq_bytes;
 168                                 spin_unlock(&mq_lock);
 169                                 goto out_inode;
 170                         }
 171                         /* all is ok */
 172                         info->user = get_uid(u);
 173                 } else if (S_ISDIR(mode)) {
 174                         inc_nlink(inode);
 175                         /* Some things misbehave if size == 0 on a directory */
 176                         inode->i_size = 2 * DIRENT_SIZE;
 177                         inode->i_op = &mqueue_dir_inode_operations;
 178                         inode->i_fop = &simple_dir_operations;
 179                 }
 180         }
 181         return inode;
 182 out_inode:
 183         make_bad_inode(inode);
 184         iput(inode);
 185         return NULL;
 186 }
 187
 188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 189 {
 190         struct inode *inode;
 191
 192         sb->s_blocksize = PAGE_CACHE_SIZE;
 193         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 194         sb->s_magic = MQUEUE_MAGIC;
 195         sb->s_op = &mqueue_super_ops;
 196
 197         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 198         if (!inode)
 199                 return -ENOMEM;
 200
 201         sb->s_root = d_alloc_root(inode);
 202         if (!sb->s_root) {
 203                 iput(inode);
 204                 return -ENOMEM;
 205         }
 206
 207         return 0;
 208 }
 209
 210 static int mqueue_get_sb(struct file_system_type *fs_type,
 211                          int flags, const char *dev_name,
 212                          void *data, struct vfsmount *mnt)
 213 {
 214         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
 215 }
 216
 217 static void init_once(void *foo)
 218 {
 219         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 220
 221         inode_init_once(&p->vfs_inode);
 222 }
 223
 224 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 225 {
 226         struct mqueue_inode_info *ei;
 227
 228         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 229         if (!ei)
 230                 return NULL;
 231         return &ei->vfs_inode;
 232 }
 233
 234 static void mqueue_destroy_inode(struct inode *inode)
 235 {
 236         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 237 }
 238
 239 static void mqueue_delete_inode(struct inode *inode)
 240 {
 241         struct mqueue_inode_info *info;
 242         struct user_struct *user;
 243         unsigned long mq_bytes;
 244         int i;
 245
 246         if (S_ISDIR(inode->i_mode)) {
 247                 clear_inode(inode);
 248                 return;
 249         }
 250         info = MQUEUE_I(inode);
 251         spin_lock(&info->lock);
 252         for (i = 0; i < info->attr.mq_curmsgs; i++)
 253                 free_msg(info->messages[i]);
 254         kfree(info->messages);
 255         spin_unlock(&info->lock);
 256
 257         clear_inode(inode);
 258
 259         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 260                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 261         user = info->user;
 262         if (user) {
 263                 spin_lock(&mq_lock);
 264                 user->mq_bytes -= mq_bytes;
 265                 queues_count--;
 266                 spin_unlock(&mq_lock);
 267                 free_uid(user);
 268         }
 269 }
 270
 271 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 272                                 int mode, struct nameidata *nd)
 273 {
 274         struct inode *inode;
 275         struct mq_attr *attr = dentry->d_fsdata;
 276         int error;
 277
 278         spin_lock(&mq_lock);
 279         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 280                 error = -ENOSPC;
 281                 goto out_lock;
 282         }
 283         queues_count++;
 284         spin_unlock(&mq_lock);
 285
 286         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 287         if (!inode) {
 288                 error = -ENOMEM;
 289                 spin_lock(&mq_lock);
 290                 queues_count--;
 291                 goto out_lock;
 292         }
 293
 294         dir->i_size += DIRENT_SIZE;
 295         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 296
 297         d_instantiate(dentry, inode);
 298         dget(dentry);
 299         return 0;
 300 out_lock:
 301         spin_unlock(&mq_lock);
 302         return error;
 303 }
 304
 305 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 306 {
 307         struct inode *inode = dentry->d_inode;
 308
 309         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 310         dir->i_size -= DIRENT_SIZE;
 311         drop_nlink(inode);
 312         dput(dentry);
 313         return 0;
 314 }
 315
 316 /*
 317 *       This is routine for system read from queue file.
 318 *       To avoid mess with doing here some sort of mq_receive we allow
 319 *       to read only queue size & notification info (the only values
 320 *       that are interesting from user point of view and aren't accessible
 321 *       through std routines)
 322 */
 323 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 324                                 size_t count, loff_t *off)
 325 {
 326         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 327         char buffer[FILENT_SIZE];
 328         ssize_t ret;
 329
 330         spin_lock(&info->lock);
 331         snprintf(buffer, sizeof(buffer),
 332                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 333                         info->qsize,
 334                         info->notify_owner ? info->notify.sigev_notify : 0,
 335                         (info->notify_owner &&
 336                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 337                                 info->notify.sigev_signo : 0,
 338                         pid_vnr(info->notify_owner));
 339         spin_unlock(&info->lock);
 340         buffer[sizeof(buffer)-1] = '\0';
 341
 342         ret = simple_read_from_buffer(u_data, count, off, buffer,
 343                                 strlen(buffer));
 344         if (ret <= 0)
 345                 return ret;
 346
 347         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 348         return ret;
 349 }
 350
 351 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 352 {
 353         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 354
 355         spin_lock(&info->lock);
 356         if (task_tgid(current) == info->notify_owner)
 357                 remove_notification(info);
 358
 359         spin_unlock(&info->lock);
 360         return 0;
 361 }
 362
 363 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 364 {
 365         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 366         int retval = 0;
 367
 368         poll_wait(filp, &info->wait_q, poll_tab);
 369
 370         spin_lock(&info->lock);
 371         if (info->attr.mq_curmsgs)
 372                 retval = POLLIN | POLLRDNORM;
 373
 374         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 375                 retval |= POLLOUT | POLLWRNORM;
 376         spin_unlock(&info->lock);
 377
 378         return retval;
 379 }
 380
 381 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 382 static void wq_add(struct mqueue_inode_info *info, int sr,
 383                         struct ext_wait_queue *ewp)
 384 {
 385         struct ext_wait_queue *walk;
 386
 387         ewp->task = current;
 388
 389         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 390                 if (walk->task->static_prio <= current->static_prio) {
 391                         list_add_tail(&ewp->list, &walk->list);
 392                         return;
 393                 }
 394         }
 395         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 396 }
 397
 398 /*
 399  * Puts current task to sleep. Caller must hold queue lock. After return
 400  * lock isn't held.
 401  * sr: SEND or RECV
 402  */
 403 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 404                         long timeout, struct ext_wait_queue *ewp)
 405 {
 406         int retval;
 407         signed long time;
 408
 409         wq_add(info, sr, ewp);
 410
 411         for (;;) {
 412                 set_current_state(TASK_INTERRUPTIBLE);
 413
 414                 spin_unlock(&info->lock);
 415                 time = schedule_timeout(timeout);
 416
 417                 while (ewp->state == STATE_PENDING)
 418                         cpu_relax();
 419
 420                 if (ewp->state == STATE_READY) {
 421                         retval = 0;
 422                         goto out;
 423                 }
 424                 spin_lock(&info->lock);
 425                 if (ewp->state == STATE_READY) {
 426                         retval = 0;
 427                         goto out_unlock;
 428                 }
 429                 if (signal_pending(current)) {
 430                         retval = -ERESTARTSYS;
 431                         break;
 432                 }
 433                 if (time == 0) {
 434                         retval = -ETIMEDOUT;
 435                         break;
 436                 }
 437         }
 438         list_del(&ewp->list);
 439 out_unlock:
 440         spin_unlock(&info->lock);
 441 out:
 442         return retval;
 443 }
 444
 445 /*
 446  * Returns waiting task that should be serviced first or NULL if none exists
 447  */
 448 static struct ext_wait_queue *wq_get_first_waiter(
 449                 struct mqueue_inode_info *info, int sr)
 450 {
 451         struct list_head *ptr;
 452
 453         ptr = info->e_wait_q[sr].list.prev;
 454         if (ptr == &info->e_wait_q[sr].list)
 455                 return NULL;
 456         return list_entry(ptr, struct ext_wait_queue, list);
 457 }
 458
 459 /* Auxiliary functions to manipulate messages' list */
 460 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 461 {
 462         int k;
 463
 464         k = info->attr.mq_curmsgs - 1;
 465         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 466                 info->messages[k + 1] = info->messages[k];
 467                 k--;
 468         }
 469         info->attr.mq_curmsgs++;
 470         info->qsize += ptr->m_ts;
 471         info->messages[k + 1] = ptr;
 472 }
 473
 474 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 475 {
 476         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 477         return info->messages[info->attr.mq_curmsgs];
 478 }
 479
 480 static inline void set_cookie(struct sk_buff *skb, char code)
 481 {
 482         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 483 }
 484
 485 /*
 486  * The next function is only to split too long sys_mq_timedsend
 487  */
 488 static void __do_notify(struct mqueue_inode_info *info)
 489 {
 490         /* notification
 491          * invoked when there is registered process and there isn't process
 492          * waiting synchronously for message AND state of queue changed from
 493          * empty to not empty. Here we are sure that no one is waiting
 494          * synchronously. */
 495         if (info->notify_owner &&
 496             info->attr.mq_curmsgs == 1) {
 497                 struct siginfo sig_i;
 498                 switch (info->notify.sigev_notify) {
 499                 case SIGEV_NONE:
 500                         break;
 501                 case SIGEV_SIGNAL:
 502                         /* sends signal */
 503
 504                         sig_i.si_signo = info->notify.sigev_signo;
 505                         sig_i.si_errno = 0;
 506                         sig_i.si_code = SI_MESGQ;
 507                         sig_i.si_value = info->notify.sigev_value;
 508                         sig_i.si_pid = task_tgid_nr_ns(current,
 509                                                 ns_of_pid(info->notify_owner));
 510                         sig_i.si_uid = current_uid();
 511
 512                         kill_pid_info(info->notify.sigev_signo,
 513                                       &sig_i, info->notify_owner);
 514                         break;
 515                 case SIGEV_THREAD:
 516                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 517                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 518                         break;
 519                 }
 520                 /* after notification unregisters process */
 521                 put_pid(info->notify_owner);
 522                 info->notify_owner = NULL;
 523         }
 524         wake_up(&info->wait_q);
 525 }
 526
 527 static long prepare_timeout(struct timespec *p)
 528 {
 529         struct timespec nowts;
 530         long timeout;
 531
 532         if (p) {
 533                 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
 534                         || p->tv_nsec >= NSEC_PER_SEC))
 535                         return -EINVAL;
 536                 nowts = CURRENT_TIME;
 537                 /* first subtract as jiffies can't be too big */
 538                 p->tv_sec -= nowts.tv_sec;
 539                 if (p->tv_nsec < nowts.tv_nsec) {
 540                         p->tv_nsec += NSEC_PER_SEC;
 541                         p->tv_sec--;
 542                 }
 543                 p->tv_nsec -= nowts.tv_nsec;
 544                 if (p->tv_sec < 0)
 545                         return 0;
 546
 547                 timeout = timespec_to_jiffies(p) + 1;
 548         } else
 549                 return MAX_SCHEDULE_TIMEOUT;
 550
 551         return timeout;
 552 }
 553
 554 static void remove_notification(struct mqueue_inode_info *info)
 555 {
 556         if (info->notify_owner != NULL &&
 557             info->notify.sigev_notify == SIGEV_THREAD) {
 558                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 559                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 560         }
 561         put_pid(info->notify_owner);
 562         info->notify_owner = NULL;
 563 }
 564
 565 static int mq_attr_ok(struct mq_attr *attr)
 566 {
 567         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 568                 return 0;
 569         if (capable(CAP_SYS_RESOURCE)) {
 570                 if (attr->mq_maxmsg > HARD_MSGMAX)
 571                         return 0;
 572         } else {
 573                 if (attr->mq_maxmsg > msg_max ||
 574                                 attr->mq_msgsize > msgsize_max)
 575                         return 0;
 576         }
 577         /* check for overflow */
 578         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 579                 return 0;
 580         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 581             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 582             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 583                 return 0;
 584         return 1;
 585 }
 586
 587 /*
 588  * Invoked when creating a new queue via sys_mq_open
 589  */
 590 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 591                         int oflag, mode_t mode, struct mq_attr *attr)
 592 {
 593         const struct cred *cred = current_cred();
 594         struct file *result;
 595         int ret;
 596
 597         if (attr) {
 598                 ret = -EINVAL;
 599                 if (!mq_attr_ok(attr))
 600                         goto out;
 601                 /* store for use during create */
 602                 dentry->d_fsdata = attr;
 603         }
 604
 605         mode &= ~current->fs->umask;
 606         ret = mnt_want_write(mqueue_mnt);
 607         if (ret)
 608                 goto out;
 609         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 610         dentry->d_fsdata = NULL;
 611         if (ret)
 612                 goto out_drop_write;
 613
 614         result = dentry_open(dentry, mqueue_mnt, oflag, cred);
 615         /*
 616          * dentry_open() took a persistent mnt_want_write(),
 617          * so we can now drop this one.
 618          */
 619         mnt_drop_write(mqueue_mnt);
 620         return result;
 621
 622 out_drop_write:
 623         mnt_drop_write(mqueue_mnt);
 624 out:
 625         dput(dentry);
 626         mntput(mqueue_mnt);
 627         return ERR_PTR(ret);
 628 }
 629
 630 /* Opens existing queue */
 631 static struct file *do_open(struct dentry *dentry, int oflag)
 632 {
 633         const struct cred *cred = current_cred();
 634
 635         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 636                                                   MAY_READ | MAY_WRITE };
 637
 638         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 639                 dput(dentry);
 640                 mntput(mqueue_mnt);
 641                 return ERR_PTR(-EINVAL);
 642         }
 643
 644         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 645                 dput(dentry);
 646                 mntput(mqueue_mnt);
 647                 return ERR_PTR(-EACCES);
 648         }
 649
 650         return dentry_open(dentry, mqueue_mnt, oflag, cred);
 651 }
 652
 653 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 654                 struct mq_attr __user *, u_attr)
 655 {
 656         struct dentry *dentry;
 657         struct file *filp;
 658         char *name;
 659         struct mq_attr attr;
 660         int fd, error;
 661
 662         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 663                 return -EFAULT;
 664
 665         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 666
 667         if (IS_ERR(name = getname(u_name)))
 668                 return PTR_ERR(name);
 669
 670         fd = get_unused_fd_flags(O_CLOEXEC);
 671         if (fd < 0)
 672                 goto out_putname;
 673
 674         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 675         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 676         if (IS_ERR(dentry)) {
 677                 error = PTR_ERR(dentry);
 678                 goto out_err;
 679         }
 680         mntget(mqueue_mnt);
 681
 682         if (oflag & O_CREAT) {
 683                 if (dentry->d_inode) {  /* entry already exists */
 684                         audit_inode(name, dentry);
 685                         error = -EEXIST;
 686                         if (oflag & O_EXCL)
 687                                 goto out;
 688                         filp = do_open(dentry, oflag);
 689                 } else {
 690                         filp = do_create(mqueue_mnt->mnt_root, dentry,
 691                                                 oflag, mode,
 692                                                 u_attr ? &attr : NULL);
 693                 }
 694         } else {
 695                 error = -ENOENT;
 696                 if (!dentry->d_inode)
 697                         goto out;
 698                 audit_inode(name, dentry);
 699                 filp = do_open(dentry, oflag);
 700         }
 701
 702         if (IS_ERR(filp)) {
 703                 error = PTR_ERR(filp);
 704                 goto out_putfd;
 705         }
 706
 707         fd_install(fd, filp);
 708         goto out_upsem;
 709
 710 out:
 711         dput(dentry);
 712         mntput(mqueue_mnt);
 713 out_putfd:
 714         put_unused_fd(fd);
 715 out_err:
 716         fd = error;
 717 out_upsem:
 718         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 719 out_putname:
 720         putname(name);
 721         return fd;
 722 }
 723
 724 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 725 {
 726         int err;
 727         char *name;
 728         struct dentry *dentry;
 729         struct inode *inode = NULL;
 730
 731         name = getname(u_name);
 732         if (IS_ERR(name))
 733                 return PTR_ERR(name);
 734
 735         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
 736                         I_MUTEX_PARENT);
 737         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 738         if (IS_ERR(dentry)) {
 739                 err = PTR_ERR(dentry);
 740                 goto out_unlock;
 741         }
 742
 743         if (!dentry->d_inode) {
 744                 err = -ENOENT;
 745                 goto out_err;
 746         }
 747
 748         inode = dentry->d_inode;
 749         if (inode)
 750                 atomic_inc(&inode->i_count);
 751         err = mnt_want_write(mqueue_mnt);
 752         if (err)
 753                 goto out_err;
 754         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 755         mnt_drop_write(mqueue_mnt);
 756 out_err:
 757         dput(dentry);
 758
 759 out_unlock:
 760         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 761         putname(name);
 762         if (inode)
 763                 iput(inode);
 764
 765         return err;
 766 }
 767
 768 /* Pipelined send and receive functions.
 769  *
 770  * If a receiver finds no waiting message, then it registers itself in the
 771  * list of waiting receivers. A sender checks that list before adding the new
 772  * message into the message array. If there is a waiting receiver, then it
 773  * bypasses the message array and directly hands the message over to the
 774  * receiver.
 775  * The receiver accepts the message and returns without grabbing the queue
 776  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 777  * are necessary. The same algorithm is used for sysv semaphores, see
 778  * ipc/sem.c for more details.
 779  *
 780  * The same algorithm is used for senders.
 781  */
 782
 783 /* pipelined_send() - send a message directly to the task waiting in
 784  * sys_mq_timedreceive() (without inserting message into a queue).
 785  */
 786 static inline void pipelined_send(struct mqueue_inode_info *info,
 787                                   struct msg_msg *message,
 788                                   struct ext_wait_queue *receiver)
 789 {
 790         receiver->msg = message;
 791         list_del(&receiver->list);
 792         receiver->state = STATE_PENDING;
 793         wake_up_process(receiver->task);
 794         smp_wmb();
 795         receiver->state = STATE_READY;
 796 }
 797
 798 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 799  * gets its message and put to the queue (we have one free place for sure). */
 800 static inline void pipelined_receive(struct mqueue_inode_info *info)
 801 {
 802         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 803
 804         if (!sender) {
 805                 /* for poll */
 806                 wake_up_interruptible(&info->wait_q);
 807                 return;
 808         }
 809         msg_insert(sender->msg, info);
 810         list_del(&sender->list);
 811         sender->state = STATE_PENDING;
 812         wake_up_process(sender->task);
 813         smp_wmb();
 814         sender->state = STATE_READY;
 815 }
 816
 817 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 818                 size_t, msg_len, unsigned int, msg_prio,
 819                 const struct timespec __user *, u_abs_timeout)
 820 {
 821         struct file *filp;
 822         struct inode *inode;
 823         struct ext_wait_queue wait;
 824         struct ext_wait_queue *receiver;
 825         struct msg_msg *msg_ptr;
 826         struct mqueue_inode_info *info;
 827         struct timespec ts, *p = NULL;
 828         long timeout;
 829         int ret;
 830
 831         if (u_abs_timeout) {
 832                 if (copy_from_user(&ts, u_abs_timeout,
 833                                         sizeof(struct timespec)))
 834                         return -EFAULT;
 835                 p = &ts;
 836         }
 837
 838         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 839                 return -EINVAL;
 840
 841         audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
 842         timeout = prepare_timeout(p);
 843
 844         ret = -EBADF;
 845         filp = fget(mqdes);
 846         if (unlikely(!filp))
 847                 goto out;
 848
 849         inode = filp->f_path.dentry->d_inode;
 850         if (unlikely(filp->f_op != &mqueue_file_operations))
 851                 goto out_fput;
 852         info = MQUEUE_I(inode);
 853         audit_inode(NULL, filp->f_path.dentry);
 854
 855         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 856                 goto out_fput;
 857
 858         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 859                 ret = -EMSGSIZE;
 860                 goto out_fput;
 861         }
 862
 863         /* First try to allocate memory, before doing anything with
 864          * existing queues. */
 865         msg_ptr = load_msg(u_msg_ptr, msg_len);
 866         if (IS_ERR(msg_ptr)) {
 867                 ret = PTR_ERR(msg_ptr);
 868                 goto out_fput;
 869         }
 870         msg_ptr->m_ts = msg_len;
 871         msg_ptr->m_type = msg_prio;
 872
 873         spin_lock(&info->lock);
 874
 875         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 876                 if (filp->f_flags & O_NONBLOCK) {
 877                         spin_unlock(&info->lock);
 878                         ret = -EAGAIN;
 879                 } else if (unlikely(timeout < 0)) {
 880                         spin_unlock(&info->lock);
 881                         ret = timeout;
 882                 } else {
 883                         wait.task = current;
 884                         wait.msg = (void *) msg_ptr;
 885                         wait.state = STATE_NONE;
 886                         ret = wq_sleep(info, SEND, timeout, &wait);
 887                 }
 888                 if (ret < 0)
 889                         free_msg(msg_ptr);
 890         } else {
 891                 receiver = wq_get_first_waiter(info, RECV);
 892                 if (receiver) {
 893                         pipelined_send(info, msg_ptr, receiver);
 894                 } else {
 895                         /* adds message to the queue */
 896                         msg_insert(msg_ptr, info);
 897                         __do_notify(info);
 898                 }
 899                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 900                                 CURRENT_TIME;
 901                 spin_unlock(&info->lock);
 902                 ret = 0;
 903         }
 904 out_fput:
 905         fput(filp);
 906 out:
 907         return ret;
 908 }
 909
 910 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 911                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 912                 const struct timespec __user *, u_abs_timeout)
 913 {
 914         long timeout;
 915         ssize_t ret;
 916         struct msg_msg *msg_ptr;
 917         struct file *filp;
 918         struct inode *inode;
 919         struct mqueue_inode_info *info;
 920         struct ext_wait_queue wait;
 921         struct timespec ts, *p = NULL;
 922
 923         if (u_abs_timeout) {
 924                 if (copy_from_user(&ts, u_abs_timeout,
 925                                         sizeof(struct timespec)))
 926                         return -EFAULT;
 927                 p = &ts;
 928         }
 929
 930         audit_mq_sendrecv(mqdes, msg_len, 0, p);
 931         timeout = prepare_timeout(p);
 932
 933         ret = -EBADF;
 934         filp = fget(mqdes);
 935         if (unlikely(!filp))
 936                 goto out;
 937
 938         inode = filp->f_path.dentry->d_inode;
 939         if (unlikely(filp->f_op != &mqueue_file_operations))
 940                 goto out_fput;
 941         info = MQUEUE_I(inode);
 942         audit_inode(NULL, filp->f_path.dentry);
 943
 944         if (unlikely(!(filp->f_mode & FMODE_READ)))
 945                 goto out_fput;
 946
 947         /* checks if buffer is big enough */
 948         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 949                 ret = -EMSGSIZE;
 950                 goto out_fput;
 951         }
 952
 953         spin_lock(&info->lock);
 954         if (info->attr.mq_curmsgs == 0) {
 955                 if (filp->f_flags & O_NONBLOCK) {
 956                         spin_unlock(&info->lock);
 957                         ret = -EAGAIN;
 958                         msg_ptr = NULL;
 959                 } else if (unlikely(timeout < 0)) {
 960                         spin_unlock(&info->lock);
 961                         ret = timeout;
 962                         msg_ptr = NULL;
 963                 } else {
 964                         wait.task = current;
 965                         wait.state = STATE_NONE;
 966                         ret = wq_sleep(info, RECV, timeout, &wait);
 967                         msg_ptr = wait.msg;
 968                 }
 969         } else {
 970                 msg_ptr = msg_get(info);
 971
 972                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 973                                 CURRENT_TIME;
 974
 975                 /* There is now free space in queue. */
 976                 pipelined_receive(info);
 977                 spin_unlock(&info->lock);
 978                 ret = 0;
 979         }
 980         if (ret == 0) {
 981                 ret = msg_ptr->m_ts;
 982
 983                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 984                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 985                         ret = -EFAULT;
 986                 }
 987                 free_msg(msg_ptr);
 988         }
 989 out_fput:
 990         fput(filp);
 991 out:
 992         return ret;
 993 }
 994
 995 /*
 996  * Notes: the case when user wants us to deregister (with NULL as pointer)
 997  * and he isn't currently owner of notification, will be silently discarded.
 998  * It isn't explicitly defined in the POSIX.
 999  */
1000 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1001                 const struct sigevent __user *, u_notification)
1002 {
1003         int ret;
1004         struct file *filp;
1005         struct sock *sock;
1006         struct inode *inode;
1007         struct sigevent notification;
1008         struct mqueue_inode_info *info;
1009         struct sk_buff *nc;
1010
1011         if (u_notification) {
1012                 if (copy_from_user(&notification, u_notification,
1013                                         sizeof(struct sigevent)))
1014                         return -EFAULT;
1015         }
1016
1017         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1018
1019         nc = NULL;
1020         sock = NULL;
1021         if (u_notification != NULL) {
1022                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1023                              notification.sigev_notify != SIGEV_SIGNAL &&
1024                              notification.sigev_notify != SIGEV_THREAD))
1025                         return -EINVAL;
1026                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1027                         !valid_signal(notification.sigev_signo)) {
1028                         return -EINVAL;
1029                 }
1030                 if (notification.sigev_notify == SIGEV_THREAD) {
1031                         long timeo;
1032
1033                         /* create the notify skb */
1034                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1035                         ret = -ENOMEM;
1036                         if (!nc)
1037                                 goto out;
1038                         ret = -EFAULT;
1039                         if (copy_from_user(nc->data,
1040                                         notification.sigev_value.sival_ptr,
1041                                         NOTIFY_COOKIE_LEN)) {
1042                                 goto out;
1043                         }
1044
1045                         /* TODO: add a header? */
1046                         skb_put(nc, NOTIFY_COOKIE_LEN);
1047                         /* and attach it to the socket */
1048 retry:
1049                         filp = fget(notification.sigev_signo);
1050                         ret = -EBADF;
1051                         if (!filp)
1052                                 goto out;
1053                         sock = netlink_getsockbyfilp(filp);
1054                         fput(filp);
1055                         if (IS_ERR(sock)) {
1056                                 ret = PTR_ERR(sock);
1057                                 sock = NULL;
1058                                 goto out;
1059                         }
1060
1061                         timeo = MAX_SCHEDULE_TIMEOUT;
1062                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1063                         if (ret == 1)
1064                                 goto retry;
1065                         if (ret) {
1066                                 sock = NULL;
1067                                 nc = NULL;
1068                                 goto out;
1069                         }
1070                 }
1071         }
1072
1073         ret = -EBADF;
1074         filp = fget(mqdes);
1075         if (!filp)
1076                 goto out;
1077
1078         inode = filp->f_path.dentry->d_inode;
1079         if (unlikely(filp->f_op != &mqueue_file_operations))
1080                 goto out_fput;
1081         info = MQUEUE_I(inode);
1082
1083         ret = 0;
1084         spin_lock(&info->lock);
1085         if (u_notification == NULL) {
1086                 if (info->notify_owner == task_tgid(current)) {
1087                         remove_notification(info);
1088                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1089                 }
1090         } else if (info->notify_owner != NULL) {
1091                 ret = -EBUSY;
1092         } else {
1093                 switch (notification.sigev_notify) {
1094                 case SIGEV_NONE:
1095                         info->notify.sigev_notify = SIGEV_NONE;
1096                         break;
1097                 case SIGEV_THREAD:
1098                         info->notify_sock = sock;
1099                         info->notify_cookie = nc;
1100                         sock = NULL;
1101                         nc = NULL;
1102                         info->notify.sigev_notify = SIGEV_THREAD;
1103                         break;
1104                 case SIGEV_SIGNAL:
1105                         info->notify.sigev_signo = notification.sigev_signo;
1106                         info->notify.sigev_value = notification.sigev_value;
1107                         info->notify.sigev_notify = SIGEV_SIGNAL;
1108                         break;
1109                 }
1110
1111                 info->notify_owner = get_pid(task_tgid(current));
1112                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1113         }
1114         spin_unlock(&info->lock);
1115 out_fput:
1116         fput(filp);
1117 out:
1118         if (sock) {
1119                 netlink_detachskb(sock, nc);
1120         } else if (nc) {
1121                 dev_kfree_skb(nc);
1122         }
1123         return ret;
1124 }
1125
1126 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1127                 const struct mq_attr __user *, u_mqstat,
1128                 struct mq_attr __user *, u_omqstat)
1129 {
1130         int ret;
1131         struct mq_attr mqstat, omqstat;
1132         struct file *filp;
1133         struct inode *inode;
1134         struct mqueue_inode_info *info;
1135
1136         if (u_mqstat != NULL) {
1137                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1138                         return -EFAULT;
1139                 if (mqstat.mq_flags & (~O_NONBLOCK))
1140                         return -EINVAL;
1141         }
1142
1143         ret = -EBADF;
1144         filp = fget(mqdes);
1145         if (!filp)
1146                 goto out;
1147
1148         inode = filp->f_path.dentry->d_inode;
1149         if (unlikely(filp->f_op != &mqueue_file_operations))
1150                 goto out_fput;
1151         info = MQUEUE_I(inode);
1152
1153         spin_lock(&info->lock);
1154
1155         omqstat = info->attr;
1156         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1157         if (u_mqstat) {
1158                 audit_mq_getsetattr(mqdes, &mqstat);
1159                 if (mqstat.mq_flags & O_NONBLOCK)
1160                         filp->f_flags |= O_NONBLOCK;
1161                 else
1162                         filp->f_flags &= ~O_NONBLOCK;
1163
1164                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1165         }
1166
1167         spin_unlock(&info->lock);
1168
1169         ret = 0;
1170         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1171                                                 sizeof(struct mq_attr)))
1172                 ret = -EFAULT;
1173
1174 out_fput:
1175         fput(filp);
1176 out:
1177         return ret;
1178 }
1179
1180 static const struct inode_operations mqueue_dir_inode_operations = {
1181         .lookup = simple_lookup,
1182         .create = mqueue_create,
1183         .unlink = mqueue_unlink,
1184 };
1185
1186 static const struct file_operations mqueue_file_operations = {
1187         .flush = mqueue_flush_file,
1188         .poll = mqueue_poll_file,
1189         .read = mqueue_read_file,
1190 };
1191
1192 static struct super_operations mqueue_super_ops = {
1193         .alloc_inode = mqueue_alloc_inode,
1194         .destroy_inode = mqueue_destroy_inode,
1195         .statfs = simple_statfs,
1196         .delete_inode = mqueue_delete_inode,
1197         .drop_inode = generic_delete_inode,
1198 };
1199
1200 static struct file_system_type mqueue_fs_type = {
1201         .name = "mqueue",
1202         .get_sb = mqueue_get_sb,
1203         .kill_sb = kill_litter_super,
1204 };
1205
1206 static int msg_max_limit_min = MIN_MSGMAX;
1207 static int msg_max_limit_max = MAX_MSGMAX;
1208
1209 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1210 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1211
1212 static ctl_table mq_sysctls[] = {
1213         {
1214                 .procname       = "queues_max",
1215                 .data           = &queues_max,
1216                 .maxlen         = sizeof(int),
1217                 .mode           = 0644,
1218                 .proc_handler   = &proc_dointvec,
1219         },
1220         {
1221                 .procname       = "msg_max",
1222                 .data           = &msg_max,
1223                 .maxlen         = sizeof(int),
1224                 .mode           = 0644,
1225                 .proc_handler   = &proc_dointvec_minmax,
1226                 .extra1         = &msg_max_limit_min,
1227                 .extra2         = &msg_max_limit_max,
1228         },
1229         {
1230                 .procname       = "msgsize_max",
1231                 .data           = &msgsize_max,
1232                 .maxlen         = sizeof(int),
1233                 .mode           = 0644,
1234                 .proc_handler   = &proc_dointvec_minmax,
1235                 .extra1         = &msg_maxsize_limit_min,
1236                 .extra2         = &msg_maxsize_limit_max,
1237         },
1238         { .ctl_name = 0 }
1239 };
1240
1241 static ctl_table mq_sysctl_dir[] = {
1242         {
1243                 .procname       = "mqueue",
1244                 .mode           = 0555,
1245                 .child          = mq_sysctls,
1246         },
1247         { .ctl_name = 0 }
1248 };
1249
1250 static ctl_table mq_sysctl_root[] = {
1251         {
1252                 .ctl_name       = CTL_FS,
1253                 .procname       = "fs",
1254                 .mode           = 0555,
1255                 .child          = mq_sysctl_dir,
1256         },
1257         { .ctl_name = 0 }
1258 };
1259
1260 static int __init init_mqueue_fs(void)
1261 {
1262         int error;
1263
1264         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1265                                 sizeof(struct mqueue_inode_info), 0,
1266                                 SLAB_HWCACHE_ALIGN, init_once);
1267         if (mqueue_inode_cachep == NULL)
1268                 return -ENOMEM;
1269
1270         /* ignore failues - they are not fatal */
1271         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1272
1273         error = register_filesystem(&mqueue_fs_type);
1274         if (error)
1275                 goto out_sysctl;
1276
1277         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1278                 error = PTR_ERR(mqueue_mnt);
1279                 goto out_filesystem;
1280         }
1281
1282         /* internal initialization - not common for vfs */
1283         queues_count = 0;
1284         spin_lock_init(&mq_lock);
1285
1286         return 0;
1287
1288 out_filesystem:
1289         unregister_filesystem(&mqueue_fs_type);
1290 out_sysctl:
1291         if (mq_sysctl_table)
1292                 unregister_sysctl_table(mq_sysctl_table);
1293         kmem_cache_destroy(mqueue_inode_cachep);
1294         return error;
1295 }
1296
1297 __initcall(init_mqueue_fs);